Water, that essential constituent to human life, must be of sufficient purity and quality to be viable for human consumption. Since all natural waters contain inorganic and organic substances which may be harmful to human consumption, some form of water purification is required to assure that water is of sufficient quality for drinking. Water-treatment systems generally remove the following contaminants: trace organic compounds; substances which produce color, taste and odor; pathogenic bacteria; and suspended materials. In order to meet drinking water standards of the Safe Drinking Water Act, water-treatment plants for municipalities use a combination of both physical and chemical processes. Physical treatment include screening, aeration, flocculation, sedimentation and filtration. Chemical treatment include coagulation, disinfection, oxidation, ozone purification and adsorption. While the foregoing water treatment processes are often necessary to assure a supply of safe drinking water, most of them are unnecessary for the average individual or group of individuals that depend on natural water taken directly from water holding or storage tanks which receive its water from wells, lakes, springs, streams and the like. Such tanks have capacities ranging from 1000 to 100,000 gallons. The holding period in such tanks are usually sufficient to assure that suspended matter can be removed by sedimentation, i.e. allowing the solid particles to settle to the bottom of the tank where they can be periodically removed. Alum can be added to the water to precipitate any suspended contaminants in the tank. The most common methods for assuring the purity of the water in holding or storage tanks is the use of chlorine as a disinfectant. Other methods include prechlorination in order to destroy algae and to oxidize excessive levels of organic contaminants. There is evidence that chlorine has caused the formation of cancer-causing compounds. Prechlorination also has its drawbacks because of the formation of compounds that impart a disagreeable taste to the water.
Until recently, ozone purification was used only by municipal water companies as a primary oxidation, disinfecting and deodorizing media in combination with chlorine as the secondary disinfecting media. Chlorine is required in such systems to assure that bacteria within the municipal water distribution system is killed since ozone reverts to oxygen within minutes after it is added. Ozone has the advantage over chlorine in that it kills bacteria on contact much faster than chlorine and kills viruses on contact that are not affected by chlorine. In addition, ozone kills algae spores, fungus, mold and yeast spores, oxidizes oils and sulfur, and precipitates heavy metals such as iron, aluminum, and manganese. Ozone removes color and odor in water without a residue since oxygen is the by-product of the oxidation reaction.
Since the mid 1980's, ozone generation systems have been used in the treatment of domestic holding tank water. In many rural areas, homeowners are required by insurance companies to maintain an adequate supply of water in holding tanks for use in the event of a fire. Such homeowners have installed ozone generation systems to make their water suitable for drinking. Purification systems currently in use for domestic tank water include an air pump, an ozone generator which is connected to an in-line mixer and which is installed on the feed line from the source to the holding tank; see Triple O Water Treatment System Model TWTS-101 sales brochure. When the water pump is on and is adding water to the holding tank, the air pump pressures air through the ozone generator and then pressures the resulting ozone-containing gas into the in-line mixer which creates ozone-saturated water bubbles. These bubbles are then pressured into a filter module which is hung inside the tank. When the water pump is off, the ozone from the generator is pressured directly to the filter module which is equipped with a diffuser to create ozone-saturated bubbles within the tank.
There is a need for a system for treating domestic holding tank water more efficiently with greater versatility than those systems which use pressure to force the ozone-containing output from the generator into the holding tank water. There is also a need for such a system which enables one to easily vary the position of the ozone-containing output in any position within the tank.